>>> act of the terror. explosions hit runners and crowds at the boston marathon. the obama administration is handling the attack as an act of terror. at least two people were killed. about 100 others wounded. the first explosion knocked back runners 30 meters from the finish and another explosion hit people a short distance away. emergency services rushed to the scene. >> it's just unbelievable this would happen at an event like this. >> there was no word on the motive or who may have been responsible. investigators are working to find out whether the attack was carried out by a terrorist group from inside or outside the country. u.s. president barack obama ordered members of his administration to provide any necessary assistance. we will find out who did this. we'll find out why they did this. any responsible individuals, any responsible groups will feel the full weight of justice. >> the boston marathon is one of the biggest annual athletic events in the u.s. about 26,000 runners were taking part. >>> officials have created a no flight zone over the site of the explosion.